Knife blade



KNIFE BLADE Filed sept. '6; 195e uflnlllllllllw Ill mm I-bWHHHHlIHHL...IIIHHIIIIM WHHHUIII IN V EN TOR. cr M 541s? United States Patent O MKNIFE BLADE Albert M. Baer, New York, N. Y., assignor to Imperial KnifeAssociated Companies, Inc., New York, N. Y., a corporation of RhodeIsland Application September 6, 1956, Serial No. 608,266

1 Claim. (Cl. 30-355) This invention relates to a knife blade. Moreparticularly, my invention pertains to a knife blade of the type whichis employed in the slicing of food such, for example, as a steak knife,a vegetable knife or a carving knife. v

For many years the eld has experienced considerable diiculty inproviding a slicing knife which had and could maintain a keen cuttingedge. It was possible to so treat the blade and to pick steels of suchconstitution that the edge was hard and tough. Nevertheless, at theextreme hardness which it was desirable to impart to such blades, therewas a tendency toward brittleness. If this tendency was counteracted byhaving the blade comparatively thick immediately in back of the cuttingedge, it was not possible to secure an acute, and therefore extremelykeen, edge. On the other hand, if the cutting blade was reduced inthickness immediately in back of the cutting edge as by employing atapered, e. g., a h-ollow-ground, blade the cutting edge would chip,tear and bend under normal conditions of use. This was particularly,although not exclusively, true of blades which had been brought to ahigh Rockwell C, e. g., 56 to 6l. These blades, even though tempered,had to be handled with care, especially when they were cutting foodsresting on a hard surface.

It has been proposed to make the edge irregular as by the use of eithertiny or gross serrations. However, until the present, the cutting edgeprovided on serrated blades has never been suiciently keen and, indeedsuch blades do not perform a true shearing action but rather function bymeans of sawing, i. e., tearing, so that the resulting surface of thefood is minutely or grossly scratched and is not as smooth as isdesired.

It is the object of the present invention to provide a cutting bladewhich avoids all of the foregoing defects.

More particularly, it is an object of the present nvention to provide acutting blade of such character that, even if extremely hard, is soconfigured that it will not tend to chip, tear or bend if used in anordinary manner.

It is another object of my invention to provide a blade of the characterdescribed which, although particularly thin immediately in back of thecutting edge, is still sufficiently sturdy to reinforce the cutting edgeand thereby inhibit chipping, tearing vor bending thereof so that thecutting edge has a long, useful life.

It is another object of my invention to provide a blade of the characterdescribed which, although serrated, does not sever by sawing or abrasionand therefore leaves a clean-cut surface.

It is another object of my invention to provide a serrated blade of thecharacter described, each portion of the cutting edge of which shearsrather than saws.

Other objects of my invention will be in part obvious and in part willbe pointed out hereinafter.

My invention accordingly consists in features of construction,combinations of elements and arrangements of parts which will beexemplified in the knife hereinafter 2,825,968 Patented Mar. 11, s

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described and of which the scope of application will be indicated in theappended claim.

In the accompanying drawings, in which is shown one of the variouspossible embodiments of my invention,

Fig. 1 is a plan view of a knife constructed in accordance with myinvention;

Fig. 2 is a similar view of the opposite side of the knife;

Fig. 3 is an enlarged sectional view taken substantially along the line3 3 of Fig. l; and

Fig. 4 is a highly enlarged view in plan of a fragment of the blade inthe vicinity of the cutting edge.

Referring now in detail to the drawings, the reference numeral 10denotes a roast slicer embodying my invention. Said slicer includes theusual handle 12 in which there is inserted a tang (not shown) of a steelknife blade 14, the tang being secured in a conventional fashi-o-n as bymeans of a pair of rivets 16. The blade preferably is tempered and has ahardness of about 56 to 61 Rockwell C.

The blade is quite long, as is usual in the art, and its blunt upperedge 18 is curved slightly upwardly, as at 2t), near the tip. The lowerlongitudinal part of the blade is tapered on both faces, as byhollow-grinding, this consisting in the provision of an outwardlyconcave section having its upper edge 22 running longitudinally of theblade at approximately the longitudinal center line and its lower edgeat the cutting edge 24 of the blade. The degree lof concavity iscomparatively slight, the purpose thereof being to have the oppositefaces of the blade approximately parallel and very close to one anotherat the cutting edge whereby a minimum thickness is created at thisregion while the back of the knife from the blunt upper edge 18 to theedge 22 reinforces the hollow-ground region. The knife is hollow-groundon both sides as will be seen from inspection of Figs. 1-3. Thehollow-grinding is performed with the aid of a conventional apparatusand in a conventional manner as, for example, by slowly traversing theblade longitudinally past and in engagement with a properly positionedgrinding wheel.

After the blade is hollow-ground or otherwise tapered toward the cuttingedge as by flat grinding or by stamping, rolling or molding, the thincutting edge 24 thereof is scalloped, i. e., provided with a series ofend-to-end outwardly concave segments. Although the specic dimensions ofthese segments are not of critical importance, I have obtained excellentresults with segments that are approximately @is of an inch long andapproximately IKM of an inch deep. Each segment desirably is of circularconguration although this is not absolutely essential for satisfactoryperformance of my invention. It thus will be seen that the cutting edgeconsists of a linear set of spaced cusps 26 linked by short segmentallycircular outwardly concave spans 28.

Each of said spans is so treated on one face of the blade, as, forexample, by grinding, so as to form an acutely inclined flank 30 wherebythe lower edge of the blade is acutely tapered in a chisel like sectionto cutting sharpness. Preferably the anks 30 of the cutting edge aresmoothed after they have been formed to provide the sharpened cuttingedge so that any burrs or steel shreds that may be present in said edgeare removed. The flanks of adjacent spans meet at the ends of the spansto dene ridges 32 extending from the cusps upwardly toward the edge 18.

It now will be apparent that the cutting edge, instead of beingstraight, as is conventional in one type of blade, or instead ofconsisting, as is conventional in another type of blade, of a keencutting edge interrupted by blunt serrations, has a scalloped cuttingedge which is keen over the entire length of every individual scallop.This meansthat when the blade is sliced through material each portion ofeach concave cutting span slices into rather than tears the materialbeing cut, to leave a at, clean, cut surface.

This type of cutting edge has been found to be far more effective than astraight cutting edge. The irnprovement is believed to be due in part tothe increased effective length of cuttingV edge and in part to thedifferentv angles atwhich successive portions of the edge are presentedto the material being cut. When a straight cutting blade is drawnthrough material the actual cutting is due to the downward movement ofthe blade, i. e., movement perpendicular to the cutting edge. The aXialtranslation of the blade does not cause the cutting except insofar asthe blade maybe minutely serrated so as to saw through the material. Onthe other hand, when the blade consists of a scalloped edge in whicheach scallop is keen and the blade is drawn through material toybeV cut,while the blade is being translated axially, it is also cutting,r thecutting taking place at angles perpendicular to the curved sections ofthe sharp concave spans.

I also have found' that a blade of the foregoing construction has alonger useful life than a conventional straight cutting blade, thisbeing due, it is believed, to the fact that cutting shifts from point topoint along each of the concave cutting spans and further to the factthat the extremely thin sharp cusps are backed up and reinforced by theheavier section of the tapered, i. e., hollow-ground, blade immediatelyabove it and by the heavier section of the hollow-ground blade whichbacks up the center of the concave cutting spans. In this fashion I amable largely to prevent the chipping, tearing and bending that isinherent in an ordinary straight, cutting blade, and particularly in ahard cutting blade.

It thus will be seen that I have provided `a knife blade which achievesthe various objects of my invention and are well adapted to meet theconditions of practical use.

As various possible embodiments might be made of the above invention andas various changes might be made in the embodiment above set forth, itis to be understood that all matter herein described or shown in theaccompanying drawing is to be interpreted as illustrative and not in alimiting sense.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

A tempered hard elongated steel knife blade having a. thick blunt upperlongitudinal edge and a sharp lower serrated edge, said knife beinghollow ground on both faces thereof from a zone between saidlongitudinal edges and as thick as said upper edge to a thin zoneimmediately above said lower serrated edge, said serrated edgeconsisting of a set of spaced pointed cusps linked by short segmentallycircular downwardly concave spans, each span being flat ground over itsentire length from the thin zone to the sharp lower edge to form on oneside of the knife only flanks of chisel-like section which are ofuniform contour over the full length of each span and thereby sharpenthe lower edge of the knife, the llank of each span intersecting thetlanks of adjacent spans at the ends of each span to define ridgesrunning upwardly from the cusps to the thin zone.

References Cited in the tile of this patent UNITED STATES PATENTS1,254,563 Anderson Jan. 22, 1918 2,002,812 Hansen May 28, 1935 2,596,851Hansen May 13, 1952 2,636,267 Whitcomb Apr. 28, 1953 2,671,267 MichalekMar. 9, 1954 FOREIGN PATENTS 592,234 Great Britain Sept. 1l, 1947

